>At 2:35 PM -0400 5/16/02, Peter F. Patel-Schneider wrote:
>>TITLE: Malformed DAML+OIL Restrictions
>>DESCRIPTION: DAML+OIL allows for restrictions that are malformed.
>> Restrictions with missing components (e.g., a
>> restriction with no daml:onProperty triple) have no
>> semantic impact, even though treating them as RDF would
>> indicate that there should be some semantic import.
>> Restrictions with extra components (e.g., a restriction
>>with
>> daml:onProperty triples to more than one property) have
>> unusual and misleading semantic impact (in general equating
>> the extensions of two or more well-formed restrictions).
>> Both of these should be syntactically illegal in OWL.
>>RAISED BY: Peter F. Patel-Schneider
>>STATUS: RAISED
>>
>
>Peter - issues shouldn't include solutions (i.e. that these should
>be syntactically illegal in OWL) - maybe "Perhaps both of these
>should..." would be better wording?
>
>Also, please explain what you mean by syntactically illegal? My
>understanding is that we decided we would use RDF/XML as the
>exchange language, and triples graphs to convey meaning, so how
>would you keep these from being syntactically expressible?
>Semantically illegal I understand, syntactically I don't understand
Oh, come. We have decided to use RDF/XML as the exchange language,
but that does not require us to say that any piece of syntactically
legal RDF/XML is also syntactically legal OWL. In fact, we cannot
possibly say that, nor should we want to. OWL will of necessity
impose its own extra wellformedness conditions on RDF/XML, just as
DAML does.
Peter is correct that these should be syntactically illegal. What
that means is that an OWL parser should reject them as ill-formed on
syntactic grounds. The issue, as I understand it, is HOW to make them
syntactically illegal, ie how to state the OWL syntactic rules
properly so as to rule out such things.
Pat